Core B has continuously served all projects of the PPG for the past 18 years of funding. The functions of this core in this renewal application are divided into three divisions. Division I is responsible for the acquisition, breeding and maintenance of mouse colonies, the predominant species used for this project. This division also provides fresh cells and tissues to the various projects as well as culturing both cells and tissues. In addition to mice, Division I is also involved in the acquisition of gastrointestinal muscle samples from the Cyonomolgus monkey and from patients undergoing either gastric bypass surgery or surgery for colon cancer. In the last funding cycle a second division was added to the core, namely flow cytometry. The flow cytometry division (Division II) has been extremely successful in sorting and analyzing various populations of cells. Our recent acquisition of transgenic mice expressing either eGFP in smooth muscle cells (smMHC-cre-eGFP) or copGFP in ICC (Kit+/copGFP) has further advanced our ability to sort and analyze highly pure populations of these two cells types. These models have also been instrumental in improving our ability to reliably isolate and study either smooth muscle or ICC specific proteins. In this current funding cycle we have added a third subdivision to core B which is focused upon the generation of new transgenic mouse models (Division III). This division has already successfully generated the copGFP ICC mouse model described above and will provide the various projects with additional ICC- or smooth muscle-specific knockout or knock-in mouse models to address the specific aims of their projects. In summary, Core B is an essential and highly successful component of the PPG which continues to grow and diversify as new methodologies and approaches become available. RELEVANCE (Seeinstructions): Core B supplies animals, cells and tissues to the various projects.